Resolved ember-simple-auth deprecations

no issue

- many "The automatic session initialization is deprecated" were shown in test output due to an old method of initializing the session service
- switched to explicit session setup in the application route's `beforeModel` hook
- https://github.com/simplabs/ember-simple-auth/issues/2314

ghost/admin/app/initializers/ember-simple-auth.js

@@ -2,7 +2,6 @@ import Configuration from 'ember-simple-auth/configuration';
 import ENV from '../config/environment';
 import ghostPaths from '../utils/ghost-paths';
 import setupSession from 'ember-simple-auth/initializers/setup-session';
-import setupSessionRestoration from 'ember-simple-auth/initializers/setup-session-restoration';
 
 export default {
     name: 'ember-simple-auth',
@@ -12,6 +11,5 @@ export default {
         Configuration.load(config);
 
         setupSession(registry);
-        setupSessionRestoration(registry);
     }
 };

ghost/admin/app/routes/application.js

@@ -52,7 +52,8 @@ export default Route.extend(ShortcutsRoute, {
         this.ui.initBodyDragHandlers();
     },
 
-    beforeModel() {
+    async beforeModel() {
+        await this.session.setup();
         return this.prepareApp();
     },